A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes
Ground-coupled heat pumps usually employ fields of borehole heat exchangers (BHEs), which must be designed by suitable models. In order to validate a BHE model, it is advisable to compare the computation results with experimental data. A well-known data set was provided by Beier et al. (Geothermics...
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| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/14/4/1149 |
| _version_ | 1797395743644844032 |
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| author | Claudia Naldi Aminhossein Jahanbin Enzo Zanchini |
| author_facet | Claudia Naldi Aminhossein Jahanbin Enzo Zanchini |
| author_sort | Claudia Naldi |
| collection | DOAJ |
| description | Ground-coupled heat pumps usually employ fields of borehole heat exchangers (BHEs), which must be designed by suitable models. In order to validate a BHE model, it is advisable to compare the computation results with experimental data. A well-known data set was provided by Beier et al. (Geothermics 2011, 40) through a laboratory model usually called “sandbox”. Several authors proposed estimates of the thermal properties of the sandbox grout and sand. In this paper, we present a new estimate of those properties, obtained by means of 2D finite-element simulations that consider all the details of the experimental setup, including the thin aluminum pipe at the BHE boundary. Our results show that the measured temperatures in the fluid and in the sand can be reproduced very accurately by considering thermal conductivities 0.863 W/(mK) for the grout and 3.22 W/(mK) for the sand, volumetric heat capacities 4.6 MJ/(m<sup>3</sup>K) for the grout and 3.07 MJ/(m<sup>3</sup>K) for the sand, and a slightly enhanced heat capacity of the water contained in the BHE. The 2D simulations are validated by comparison with an analytical solution and by 3D simulations. |
| first_indexed | 2024-03-09T00:40:04Z |
| format | Article |
| id | doaj.art-e5377e15c51b4754860378248cff7e07 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-09T00:40:04Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
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| series | Energies |
| spelling | doaj.art-e5377e15c51b4754860378248cff7e072023-12-11T17:55:22ZengMDPI AGEnergies1996-10732021-02-01144114910.3390/en14041149A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation CodesClaudia Naldi0Aminhossein Jahanbin1Enzo Zanchini2Department of Industrial Engineering, School of Engineering and Architecture, Alma Mater Studiorum University of Bologna, Viale Risorgimento 2, 40136 Bologna, ItalyDepartment of Industrial Engineering, School of Engineering and Architecture, Alma Mater Studiorum University of Bologna, Viale Risorgimento 2, 40136 Bologna, ItalyDepartment of Industrial Engineering, School of Engineering and Architecture, Alma Mater Studiorum University of Bologna, Viale Risorgimento 2, 40136 Bologna, ItalyGround-coupled heat pumps usually employ fields of borehole heat exchangers (BHEs), which must be designed by suitable models. In order to validate a BHE model, it is advisable to compare the computation results with experimental data. A well-known data set was provided by Beier et al. (Geothermics 2011, 40) through a laboratory model usually called “sandbox”. Several authors proposed estimates of the thermal properties of the sandbox grout and sand. In this paper, we present a new estimate of those properties, obtained by means of 2D finite-element simulations that consider all the details of the experimental setup, including the thin aluminum pipe at the BHE boundary. Our results show that the measured temperatures in the fluid and in the sand can be reproduced very accurately by considering thermal conductivities 0.863 W/(mK) for the grout and 3.22 W/(mK) for the sand, volumetric heat capacities 4.6 MJ/(m<sup>3</sup>K) for the grout and 3.07 MJ/(m<sup>3</sup>K) for the sand, and a slightly enhanced heat capacity of the water contained in the BHE. The 2D simulations are validated by comparison with an analytical solution and by 3D simulations.https://www.mdpi.com/1996-1073/14/4/1149ground-coupled heat pumpsborehole heat exchangerssandbox experimentfinite-element simulationsestimation of thermal properties |
| spellingShingle | Claudia Naldi Aminhossein Jahanbin Enzo Zanchini A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes Energies ground-coupled heat pumps borehole heat exchangers sandbox experiment finite-element simulations estimation of thermal properties |
| title | A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes |
| title_full | A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes |
| title_fullStr | A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes |
| title_full_unstemmed | A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes |
| title_short | A New Estimate of Sand and Grout Thermal Properties in the Sandbox Experiment for Accurate Validations of Borehole Simulation Codes |
| title_sort | new estimate of sand and grout thermal properties in the sandbox experiment for accurate validations of borehole simulation codes |
| topic | ground-coupled heat pumps borehole heat exchangers sandbox experiment finite-element simulations estimation of thermal properties |
| url | https://www.mdpi.com/1996-1073/14/4/1149 |
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